In certain secure devices such as payment cards, integrated circuit chips are likely to process and/or store critical data, for example, encryption keys. Such chips may be fraudulently manipulated in order to obtain protected confidential data.
To intentionally cause disturbances in the circuits of a chip, an attack mode comprises bombarding chip areas with a laser beam while the chip is operating. Due to the presence of interconnection metal tracks on the front surface side of the chip, laser attacks are often carried out on the back side.
To avoid fraud, chips comprising attack detection devices have been provided. The attack detection device is coupled to a chip protection circuit. When an attack is detected, the protection circuit implements certain measures of protection, modification, or destruction of the critical data. For example, it may be provided, when an attack is detected, to interrupt the power supply of the chip or to cause it to reset, in order to reduce the time during which the attacker can study the chip response to a disturbance.
Existing detection devices have various disadvantages. They require, for example, creating new structures on chip to enable the detection of a laser attack. Further, they may increase the bulk and/or the complexity of secure devices.